The present invention relates to a power window driving device for controlling a power window provided in a vehicle and more particularly to the art of preventing the misreversing of a power window while the vehicle provided with the power window driving device drives on a rough and bumpy road.
The window glass of power windows mounted on the vehicle is connected to a drive motor and by throwing switches reversibly to rotate the drive motors, the window glasses move upward or downward. Moreover, some power window that has been proposed and put to practical use functions as what prevents damage to not only the obstacle caught in the power window but also the power window itself while the window glass is moving upward by stopping the drive motor and further reversing the rotating direction of the drive motor so as to move the window glass downward.
With such a related power window driving device, the art of suspending the operation of and reversing direction of the drive motor is disclosed in JP-A-10-25964 (FIG. 1) in which a driving device is suspended and reversed when an obstacle is so pinched in the power window that an increase of the electric current flowing through the drive motor exceeds a predetermined level.
With the related power window driving device, however, there may arise malfunction that the power window is stopped and moved reversely when the current flowing into the drive motor fluctuates, although any obstacle is not actually caught in the power window.
This kind of occurrence is often caused by rough roads on which vehicles travel. When the window glass is moved upward while a vehicle is traveling on a rough road, the window-glass driving force varies with the vibration (up and down motion) of the vehicle body and so does the current flowing into the drive motor. Consequently, the problem is that the power window driving device tends to misjudge that an obstacle is actually caught in the power window and then operates to move the window glass reversely.